Modal Analysis of a Gearbox Housing in Order to Avoid Resonance Frequencies

2020 ◽  
pp. 343-350
Author(s):  
Attila Gerocs ◽  
Zoltan Korka ◽  
Vasile Cojocaru ◽  
Calin-Octavian Miclosina
Keyword(s):  
Modal Analysis ◽  
Resonance Frequencies

Grass trimmer hand-arm vibration reduction using multi-axial vibration absorber

2019 ◽  
Vol 50 (8) ◽  
pp. 245-253
Author(s):  
Sushil S Patil
Keyword(s):  
Modal Analysis ◽  
Vibration Reduction ◽  
Experimental Tests ◽  
Experimental Modal Analysis ◽  
Petrol Engine ◽  
Vibration Absorber ◽  
The Novel ◽  
Axial Vibration ◽  
Substantial Level ◽  
Resonance Frequencies

In this investigation, the novel multi-axial vibration absorber is proposed to reduce the handle vibration of petrol engine grass trimmer. The proposed vibration absorber is designed using Dunkerley’s equation and fabricated for testing. The experimental modal analysis of absorber is conducted to find resonance frequencies of the absorber and to validate the results obtained from equations. The experimental tests are carried on grass trimmer with absorber attached near handle location to find effectiveness of absorber in reducing hand-arm vibrations in the x, y and z directions. The result indicated that the total vibration value measured at the handle of grass trimmer is reduced by substantial level with the attachment of multi-axial vibration absorber.

Modeling and Analysis of Piezoelectric Energy Harvesting Beams Using the Dynamic Stiffness and Analytical Modal Analysis Methods

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
P. Bonello ◽  
S. Rafique
Keyword(s):  
Energy Harvesting ◽  
Modal Analysis ◽  
Theoretical Study ◽  
Dynamic Stiffness ◽  
Piezoelectric Energy Harvesting ◽  
Arbitrary Boundary ◽  
Modeling And Analysis ◽  
Piezoelectric Energy ◽  
Resonance Frequencies ◽  
Tip Mass

The modeling and analysis of base-excited piezoelectric energy harvesting beams have attracted many researchers with the aim of predicting the electrical output for a given base motion input. Despite this, it is only recently that an accurate model based on the analytical modal analysis method (AMAM) has been developed. Moreover, single-degree-of-freedom models are still being used despite the proven potential for significant error. One major disadvantage of the AMAM is that it is restricted to simple cantilevered uniform-section beams. This paper presents two alternative modeling techniques for energy harvesting beams and uses these techniques in a theoretical study of a bimorph. One of the methods is a novel application of the dynamic stiffness method (DSM) to the modeling of energy harvesting beams. This method is based on the exact solution of the wave equation and so obviates the need for modal transformation. The dynamic stiffness matrix of a uniform-section beam could be used in the modeling of beams with arbitrary boundary conditions or assemblies of beams of different cross sections. The other method is a much-needed reformulation of the AMAM that condenses the analysis to encompass all previously analyzed systems. The Euler–Bernoulli model with piezoelectric coupling is used and the external electrical load is represented by generic linear impedance. Simulations verify that, with a sufficient number of modes included, the AMAM result converges to the DSM result. A theoretical study of a bimorph investigates the effect of the impedance and quantifies the tuning range of the resonance frequencies under variable impedance. The neutralizing effect of a tuned harvester on the vibration at its base is investigated using the DSM. The findings suggest the potential of the novel concept of a variable capacitance adaptive vibration neutralizer that doubles as an adaptive energy harvester. The application of the DSM to more complex systems is illustrated. For the case studied, a significant increase in the power generated was achieved for a given working frequency through the application of a tip rotational restraint, the use of segmented electrodes, and a resized tip mass.

Modal Analysis of Gallium Nitride Membrane for Pressure Sensing Device

2014 ◽  
Vol 605 ◽  
pp. 404-407 ◽  
Author(s):  
Jaroslav Dzuba ◽  
Milan Držík ◽  
Gabriel Vanko ◽  
Ivan Rýger ◽  
Martin Vallo ◽  
...  
Keyword(s):  
Residual Stress ◽  
Gallium Nitride ◽  
Modal Analysis ◽  
Membrane Surface ◽  
Vibration Measurement ◽  
High Electron ◽  
Frequency Method ◽  
Initial Stress State ◽  
Pressure Sensing ◽  
Resonance Frequencies

A circular high electron mobility transistor (C-HEMT) prepared on the AlGaN/GaN membrane surface has been investigated and its potential for pressure sensing has been already demonstrated. The key issue in the design process of such heterostructure based MEMS sensors is the stress engineering. This way we can scale the sensor performance, measured pressure range and sensitivity. Especially, the knowledge of the exact value of the residual stress in membranes (caused by deposition process) helps us to optimize the sensing devices. In this work, the residual stress determination method in gallium nitride circular shaped membrane is reported. It is shown that resonant frequency method using Laser Doppler Vibrometry (LDV) for membrane vibration measurement seems to be an appropriate technique to determine the residual stress in micro-scale membranes. Circularly shaped AlGaN/GaN micro-membranes are excited by acoustic short time pulse. The decay oscillating motion of the membrane is recorded by oscilloscope. By FFT spectral analysis of the signals the resonance frequencies are obtained. For the sample studied, the natural frequency mode resonance peak is used to define the residual stress level. To verify the observed stress in investigated membranes, prestressed modal analysis in finite element method (FEM) code ANSYS is performed. The stress extracted from the measured frequency is taken as an initial stress state of the modelled membrane. Experimentally obtained shock spectra are compared with that computed by FEM simulation.

Modal Analysis of Flip Chip for Solder Bump Defect Detection

2012 ◽  
Vol 468-471 ◽  
pp. 2104-2110
Author(s):  
Jun Chao Liu ◽  
Tie Lin Shi ◽  
Ke Wang ◽  
Miao Zeng ◽  
Guang Lan Liao
Keyword(s):  
Modal Analysis ◽  
Defect Detection ◽  
Flip Chip ◽  
Solder Bump ◽  
Ultrasonic Waves ◽  
Critical Element ◽  
Inspection Method ◽  
Chip Technology ◽  
Solder Bumps ◽  
Resonance Frequencies

Flip chip technology is one of the fastest growing segments of microelectronics packaging because of its ability to satisfy the increasing demands of high input/output density, package miniaturization, and reduced cost. A critical element in the successful application of flip chip technology is the reliability of solder bumps. In this paper, a nondestructive inspection method combining ultrasonic excitation with modal analysis is proposed for flip-chip solder bump defect detection. The signal generator and power amplifier are utilized to drive the capacitive air-coupled ultrasonic transducer to produce continuous ultrasonic waves for exciting the test chips. The vibration velocities of the chips are measured by the laser scanning vibrometer to extract the modal shapes and resonance frequencies. The results prove that the defective chips can be distinguished from the good chip by the modal shapes, and the resonance frequencies of the chips decrease with the increase of the open solder bumps. Therefore, this detection method may provide a new path for the improvement and innovation of flip chip on-line inspection systems.

Towards mechanical modeling of rock glaciers from modal analysis of passive seismic data

2020 ◽  
Author(s):  
Antoine Guillemot ◽  
Laurent Baillet ◽  
Stéphane Garambois ◽  
Xavier Bodin ◽  
Éric Larose ◽  
...  
Keyword(s):  
Modal Analysis ◽  
Elastic Properties ◽  
Seasonal Variations ◽  
Ambient Noise ◽  
Geophysical Methods ◽  
Mechanical Modeling ◽  
Rock Glacier ◽  
Resonance Frequencies ◽  
Passive Seismic ◽  
Rock Glaciers

<p>Among mountainous landforms, rock glaciers are mostly abundant in periglacial areas, as tongue-shaped heterogeneous bodies. By measuring physical properties sensitive to useful hydro-mechanical parameters of the medium, a wide range of geophysical methods provides interesting tools to characterize and monitor rock glaciers at large scale<sup>(1)</sup>. However, the need of high resolution temporal monitoring reduces the choice of such methods.</p><p>Passive seismic monitoring systems have the potential to overcome these difficulties, as recently shown on the Gugla rock glacier<sup>(2)</sup>. Indeed, seismological networks provide continuous recordings of both seismic ambient noise and microseismicity. From spectral analysis, we track resonance frequencies and modal parameters that are directly linked to elastic properties of the system, which evolve according to its rigidity and its density<sup>(3)(4)</sup>. Here, we propose to evaluate the potential of this methodology on two rock glaciers (Laurichard and Gugla) located in the Alps, at elevations where climatic forcing influences their internal structures and consequently their dynamics.</p><p>For both sites, we succeed in tracking and monitoring resonance frequencies of vibrating modes during several years. These frequencies show seasonal variations, indicating a freeze-thawing effect on elastic properties of the structure.</p><p>Assuming vibrating systems, we perform 2D mechanical modeling of rock glaciers, which fits well the recorded resonant frequencies. By modeling the increase of rigidity due to freezing in wintertime, seasonal variations are also mimicked. Differences between observed and modeled values, together with the variability of the results over sites, are discussed.</p><p>We finally compare the results of modal analysis with those from Ground Penetrating Radar surveys, in order to converge on a consistent view of these rock glaciers and their freeze-thawing cycles.</p><p> </p><p><strong>References</strong></p><ul><li>(1) Kneisel, C., Hauck, C., Fortier, R., Moorman, B., (2008). Advances in geophysical methods for permafrost investigations. Permafrost and Periglacial Processes 19, 157–178. https://doi.org/10.1002/ppp.616</li> <li>(2) Guillemot A., Baillet L., Helmstetter A., Larose E., Garambois S., Mayoraz R., (2019). Seismic monitoring in the Gugla rock glacier (Switzerland): ambient noise correlation, microseismicity and modelling, Geophysical Journal International, submitted.</li> <li>(3) Roux Ph., Guéguen Ph., Baillet L., Hamze A. (2014). Structural-change localization and monitoring through a perturbation-based inverse problem, The Journal of the Acoustical Society of America 136, 2586; https://doi.org/10.1121/1.4897403</li> <li>(4) Larose E., C. S. (2015). Environmental seismology: What ca we learn on earth surface processes with ambient noise. Journal of Applied Geophysics, 116, 62-74.</li> </ul>

scholarly journals Vibroacoustic Analysis of a Refrigerator Freezer Cabinet Coupled with an Air Duct

2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Onur Çelikkan ◽  
Haluk Erol
Keyword(s):  
Modal Analysis ◽  
Mixed Finite Element ◽  
Normal Modes ◽  
Mixed Finite Element Method ◽  
Validation Process ◽  
Acoustic Characteristics ◽  
Resonance Frequencies ◽  
Experimental Analyses ◽  
Acoustic Fluid ◽  
Good Agreement

In this study, the vibration and acoustic interactions between the structure and the cavity inside the freezer cabinet were investigated. Thus, a set of numerical and experimental analyses were performed. In the numerical analysis, the acoustic characteristics of the freezer cavity were solved, and the mixed finite element method was then implemented to analyse the coupled behaviour of the cavity with the air duct using the Acoustic Fluid-Structure Interaction (AFSI) technique. In the experimental analyses, an acoustic modal analysis of the freezer cavity and a structural modal analysis of the air duct were performed for the validation process. A good agreement was obtained among the results. Thus, the accuracy of the numerical model was confirmed. The validated models were used for optimizing the design. To solve the noise generation mechanism inside the freezer cabinet, the noise primarily generated by the freezer fan unit was measured under normal working conditions of the refrigerator, and the resonance frequencies were obtained. This information was compared with the normal modes of the air duct, and the overlapping frequencies were identified. To reduce the interaction between the source and the structure, a few design modifications were applied to the air duct. Thus, the structural-borne noise radiating from the air duct into the freezer cavity was reduced.

scholarly journals Rolling shear modulus and damping factor of spruce and decayed spruce estimated by modal analysis

Holzforschung ◽  
2006 ◽  
Vol 60 (1) ◽  
pp. 78-84 ◽  
Author(s):  
Sandy Isabelle Schubert ◽  
Daniel Gsell ◽  
Jürg Dual ◽  
Masoud Motavalli ◽  
Peter Niemz
Keyword(s):  
Theoretical Model ◽  
Shear Modulus ◽  
Modal Analysis ◽  
Norway Spruce ◽  
Least Squares Method ◽  
White Rot ◽  
Heterobasidion Annosum ◽  
Damping Factor ◽  
Rolling Shear ◽  
Resonance Frequencies

AbstractModal analysis was used to determine the rolling shear modulus of Norway spruce samples that were either untreated or inoculated with fungi. The resonance frequencies of centimeter-range cuboids were measured using contact-less laser interferometry. A three-dimensional theoretical model describing the orthotropic behavior of the material was used to calculate the resonance frequencies. Using an iterative scheme based on the least-squares method, the value of the rolling shear modulus was then extracted. In this first investigation, the decrease in the rolling shear modulus and the weight loss of Norway spruce inoculated with white-rot fungiHeterobasidion annosumandGanoderma lipsiensewere studied for three different exposure times ranging from 4 to 12 weeks. Comparison of measured and theoretical resonance frequencies confirmed that operation was in the applicable range of the theoretical model for the inoculated specimens. A decrease in rolling shear modulus of up to 10% (H. annosum) and 50% (G. lipsiense) was found.

Modal Analysis of Turbulent Flow near an Inclined Bank–Longitudinal Structure Junction

2021 ◽  
Vol 147 (3) ◽  
pp. 04020100
Author(s):  
Nasser Heydari ◽  
Panayiotis Diplas ◽  
J. Nathan Kutz ◽  
Soheil Sadeghi Eshkevari
Keyword(s):  
Turbulent Flow ◽  
Modal Analysis ◽  
Longitudinal Structure
Sign in / Sign up

Export Citation Format

Share Document